The political drama surrounding an ambitious Chinese Communist party leader, his former ally a "robocop" police chief who apparently tried to defect to the west, a missing businessman, and another who claims to have been tortured, has uncovered bitter tensions in the Communist party as a new generation of leaders prepares to take power.

Bo Xilai, the communist party boss of the Chinese city of Chongqing and until recently one of the party's most up-and-coming figures, fought back on Friday in his first public comments since his former collaborator's fall from grace. Bo denied he had offered to resign, and hit out at critics who had "poured filth" on him and his family, at a briefing on the sidelines of the usually staid National People's Congress.

His downfall has given a rare glimpse of schisms within the party. "The intrigues behind the scenes are always there; it is a question of whether they are allowed to come out," said Professor Steve Tsang, an expert on Chinese politics at Nottingham University. He suggested leaders had probably cut a deal so that Bo would be neither promoted nor demoted.

Bo said his former ally Wang Lijun's flight to the US consulate in nearby Chengdu last month had surprised him. "I truly never expected this to happen. I felt it was extremely sudden," he said.

Wang, the vice-mayor and police boss of the city, made his move after being sidelined days before amid rumours of corruption. He left of his own volition, according to the US, and is now under investigation.

Bo said he was responsible for what happened in Chongqing and dismissed rumours he had offered to resign as "totally imaginary". His profile soared last year after he launched a dramatic anti-gang campaign, spearheaded by Wang, and a "red culture" drive in Chongqing. Many believed he would win a position on the Politburo standing committee, the nine-member body at the top of Chinese politics, which will be unveiled at the party congress this autumn.

"I've never associated myself with any notions about the 18th congress," he told reporters. Bo boasts an impeccable family background as the son of communist "immortal" Bo Yibo, and has been lauded as a leader who appeals to ordinary people and knows how to get things done. But he is a highly divisive figure. Liberals said the crime campaign trampled over basic rights, while others fear him as a potential strongman, say analysts.

Bo's appearance was awaited with particular eagerness after he was the only one of the Politburo's 25 members absent from an NPC session on Thursday. He said that he had a cough.

Meanwhile, a Chongqing businessman appears to have vanished in Beijing shortly after publishing a microblog message saying "the jigsaw puzzle around Wang Lijun" would soon become clear. Zhang Mingyu had claimed to have a recording of Wang warning him to stop accusing another businessman of corruption. Zang's lawyer, Pu Zhiqiang, said Zhang had been visited by police and other officials who wanted him to return to Chongqing, and was now out of contact. Questioning their jurisdiction, Pu added: "Chongqing police came to Beijing to take him. This is more like a kidnapping." Chongqing police said they had no information on Zhang.

Earlier this week fugitive Chinese businessman Li Jun described Bo's anti-crime campaign as a "red terror". He alleged in interviews with the Financial Times and Washington Post that Chongqing security officials had tortured him and seized his assets. Chongqing officials declined to comment.

Bo said fighting organised crime was bound to offend some people from certain interest groups. "Should we be deaf and pretend not to deal with gangsters or face them and crack down on them and provide a good society for the people?" he asked, adding that the public had welcomed the campaign. He said his family did not have assets, and denied reports his son, Bo Guagua, drove a Ferrari. He also insisted his son had received a full scholarship to Oxford – there had been speculation about how the family paid the fees.

"These people who have formed criminal blocs have wide social ties and the ability to shape opinion," Bo said. "There are also, for example, people who have poured filth on Chongqing, and poured filth on myself and my family." Bo also indicated inequality in China had hit a high level, saying the gini coefficient – the most commonly used measure of inequality – had exceeded 0.46, a similar level to the United States and well past the 0.4 figure often seen as an indicator of growing social tension. China's statistics bureau has said it cannot produce a single national figure because of problems with the survey method. Bo said reducing the wealth gap was a major task for Chongqing, adding: "If only a few people are rich then we'll slide into capitalism. We've failed."